Koi Fish

Category: Sea Life

Koi are actually a domesticated designer variety of the common carp (Cyprinus caprio). They are highly variable in color but are often quite striking, making them a decorative staple in ponds and gardens.

Koi Fish

Koi Fish

Scientific & Common Names

Kingdom - Animalia

Phylum - Chordata

Class - Aptinopterygii

Order - Cypriniformes

Family - Cyprinidae

Genus – Cyprinus

Species & Subspecies – C. carpio haematopterus or C. rubrofuscus

Common Names – Koi, Nishikigoi (Japanese), Amur carp (non-domesticated)


There are many varieties of koi that are categorized by their scales, coloration and pattern. They can vary greatly in color, with white, black, red, yellow, blue, and cream being the most common. The common carp is a large, dull grey bottom-feeding fish, though the colorful koi have been bred in Japan for centuries.


Koi reproduce by spawning, with a female laying eggs and a male fertilizing them. They typically give birth to thousands of offspring, and the color and patterning are not necessarily reflective of the parental genes, unlike other carefully bred animals like dogs, cows or goldfish. Raising koi and selectively breeding for desired coloration is a difficult process that is often left to dedicated professionals.


Koi feed on a variety of vegetables. Though carp are naturally bottom-feeders, koi are typically fed with floating food so that they will congregate at the surface to better show off their striking colors. This also allows them to be checked for parasites and disease. Koi are very hardy fish that resist most common fish ailments, though there are a few specific carp diseases that can be detrimental.

Koi are long-lived fish, known to live for more than 50 years. There are some anecdotal reports that koi can live for 100 or even 200 years.



Koi have been bred in Japan for decorative coloration for more than a thousand years, though the rest of the world was not aware of this practice until the early 20th century. There are dozens of named varieties, and the possibilities for color and pattern combinations are nearly endless.

Though koi are similar to goldfish (the domesticated Prussian carp), they are typically larger with less variety in their body shape and fin styles. Koi can also be identified by the barbels on their lips, which goldfish do not possess.

Present status

Koi are a domesticated species and are in no danger of extinction. In fact, they are considered an invasive species, and koi can be found in the wild in the waters of every continent aside from Antarctica. Koi often make the waters they inhabit murky due to their bottom-feeding habits and are considered a pest. Within a few generations of offspring, wild koi will produce dull-colored offspring indistinguishable from the common carp.